Synthesis and characterization of TiO 2 nanotubes doped with Fe via in situ Anodization

The aim of this paper was to study the effect of Fe at low concentration in self-organized titania nanotube (TNT) arrays by using a convenient one-step synthesis process. The synthesis was done by electrochemical anodization of titanium sheets in an electrolyte solution formed by ethylene glycol (EG), ammonium fluoride (NH4F) and deionized water. Iron was also added to the electrolyte in various quantities to prepare 0.005, 0.007, 0.01, 0.012 and 0.014 M solution of Fe(NO3)3·9H2O. The prepared nanotubes were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), UV–vis spectroscopy (UV–vis) and Raman spectroscopy. Iron ions influence the morphology of the obtained TiO2. In addition, iron also changes the band gap energy of the resulted materials. A decrease in the band gap energy to 2.94 eV was observed for 2.4Fe-TNT containing the highest amount of iron tested, compared to 3.27 eV of pure 0.0Fe-TNT. Thus, this convenient iron doping of the TNT leads to a significant photoresponse of the material in the visible light region.